This invention relates generally to a protection circuit for electro-mechanical devices, and more particularly, to such a circuit for protecting tape punching computer systems.
Many of the computer systems utilized today include some form of paper tape having holes appropriately punched, thus storing information. This is particularly true where the system includes remote data links connected to a central data base. Generally, these remote links have a device resembling a common typewriter with an adapter for accepting a telephone hand set and a tape punching system. The tape punching system provides a small convenient, reproducible record of the data input to the computer.
One difficulty exists with tape punch systems, and that arises where power to the system, either completely fails, or is interrupted for some reason. When this situation occurs, the system must be completely recycled. Unlatched clutches will suffer excessive wear and quickly fail if recycling does not take place. Simple recycling has its own inherent difficulties in that the process causes extraneous holes to be punched in the tape and thereby raising the possibility of feeding improper data to the central computer.
This situation could be easily remedied by simply having the operator remove the tape and feed a separate, discardable tape through the tape punching system. However, in the case where the power failure is transistory or, is in fact a lowering of voltage momentarily, the operator may not be aware of the failure and hence, the extra holes punched with the resultant effects on the computer.
Various approaches have been tried to remedy the situation and none have thus far been successful. For example, integrated circuits have been considered to protect the tape punch system. However, the drive motor of the system has generated excessive noise for a fast, sensitive circuit. When an integrated circuit is designed to operate with the motor noise, it is too slow and lacks the sensitivity required to protect the system.
The invention described hereinafter avoids the difficulties of the prior art and provides a system of automatic protection for tape punch systems.